2 * Blackfin On-Chip Watchdog Driver
3 * Supports BF53[123]/BF53[467]/BF54[2489]/BF561
5 * Originally based on softdog.c
6 * Copyright 2006-2007 Analog Devices Inc.
7 * Copyright 2006-2007 Michele d'Amico
8 * Copyright 1996 Alan Cox <alan@redhat.com>
10 * Enter bugs at http://blackfin.uclinux.org/
12 * Licensed under the GPL-2 or later.
15 #include <linux/platform_device.h>
16 #include <linux/module.h>
17 #include <linux/moduleparam.h>
18 #include <linux/types.h>
19 #include <linux/timer.h>
20 #include <linux/miscdevice.h>
21 #include <linux/watchdog.h>
23 #include <linux/notifier.h>
24 #include <linux/reboot.h>
25 #include <linux/init.h>
26 #include <linux/interrupt.h>
27 #include <asm/blackfin.h>
28 #include <asm/uaccess.h>
30 #define stamp(fmt, args...) pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args)
31 #define stampit() stamp("here i am")
32 #define pr_devinit(fmt, args...) ({ static const __devinitconst char __fmt[] = fmt; printk(__fmt, ## args); })
33 #define pr_init(fmt, args...) ({ static const __initconst char __fmt[] = fmt; printk(__fmt, ## args); })
35 #define WATCHDOG_NAME "bfin-wdt"
36 #define PFX WATCHDOG_NAME ": "
38 /* The BF561 has two watchdogs (one per core), but since Linux
39 * only runs on core A, we'll just work with that one.
42 # define bfin_read_WDOG_CTL() bfin_read_WDOGA_CTL()
43 # define bfin_read_WDOG_CNT() bfin_read_WDOGA_CNT()
44 # define bfin_read_WDOG_STAT() bfin_read_WDOGA_STAT()
45 # define bfin_write_WDOG_CTL(x) bfin_write_WDOGA_CTL(x)
46 # define bfin_write_WDOG_CNT(x) bfin_write_WDOGA_CNT(x)
47 # define bfin_write_WDOG_STAT(x) bfin_write_WDOGA_STAT(x)
50 /* Bit in SWRST that indicates boot caused by watchdog */
51 #define SWRST_RESET_WDOG 0x4000
53 /* Bit in WDOG_CTL that indicates watchdog has expired (WDR0) */
54 #define WDOG_EXPIRED 0x8000
56 /* Masks for WDEV field in WDOG_CTL register */
57 #define ICTL_RESET 0x0
63 /* Masks for WDEN field in WDOG_CTL register */
64 #define WDEN_MASK 0x0FF0
65 #define WDEN_ENABLE 0x0000
66 #define WDEN_DISABLE 0x0AD0
69 #define WATCHDOG_TIMEOUT 20
71 static unsigned int timeout
= WATCHDOG_TIMEOUT
;
72 static int nowayout
= WATCHDOG_NOWAYOUT
;
73 static struct watchdog_info bfin_wdt_info
;
74 static unsigned long open_check
;
75 static char expect_close
;
76 static DEFINE_SPINLOCK(bfin_wdt_spinlock
);
79 * bfin_wdt_keepalive - Keep the Userspace Watchdog Alive
81 * The Userspace watchdog got a KeepAlive: schedule the next timeout.
83 static int bfin_wdt_keepalive(void)
86 bfin_write_WDOG_STAT(0);
91 * bfin_wdt_stop - Stop the Watchdog
93 * Stops the on-chip watchdog.
95 static int bfin_wdt_stop(void)
98 bfin_write_WDOG_CTL(WDEN_DISABLE
);
103 * bfin_wdt_start - Start the Watchdog
105 * Starts the on-chip watchdog. Automatically loads WDOG_CNT
106 * into WDOG_STAT for us.
108 static int bfin_wdt_start(void)
111 bfin_write_WDOG_CTL(WDEN_ENABLE
| ICTL_RESET
);
116 * bfin_wdt_running - Check Watchdog status
118 * See if the watchdog is running.
120 static int bfin_wdt_running(void)
123 return ((bfin_read_WDOG_CTL() & WDEN_MASK
) != WDEN_DISABLE
);
127 * bfin_wdt_set_timeout - Set the Userspace Watchdog timeout
128 * @t: new timeout value (in seconds)
130 * Translate the specified timeout in seconds into System Clock
131 * terms which is what the on-chip Watchdog requires.
133 static int bfin_wdt_set_timeout(unsigned long t
)
140 cnt
= t
* get_sclk();
141 if (cnt
< get_sclk()) {
142 printk(KERN_WARNING PFX
"timeout value is too large\n");
146 spin_lock_irqsave(&bfin_wdt_spinlock
, flags
);
148 int run
= bfin_wdt_running();
150 bfin_write_WDOG_CNT(cnt
);
151 if (run
) bfin_wdt_start();
153 spin_unlock_irqrestore(&bfin_wdt_spinlock
, flags
);
161 * bfin_wdt_open - Open the Device
162 * @inode: inode of device
163 * @file: file handle of device
165 * Watchdog device is opened and started.
167 static int bfin_wdt_open(struct inode
*inode
, struct file
*file
)
171 if (test_and_set_bit(0, &open_check
))
175 __module_get(THIS_MODULE
);
177 bfin_wdt_keepalive();
180 return nonseekable_open(inode
, file
);
184 * bfin_wdt_close - Close the Device
185 * @inode: inode of device
186 * @file: file handle of device
188 * Watchdog device is closed and stopped.
190 static int bfin_wdt_release(struct inode
*inode
, struct file
*file
)
194 if (expect_close
== 42) {
197 printk(KERN_CRIT PFX
"Unexpected close, not stopping watchdog!\n");
198 bfin_wdt_keepalive();
202 clear_bit(0, &open_check
);
208 * bfin_wdt_write - Write to Device
209 * @file: file handle of device
210 * @buf: buffer to write
211 * @count: length of buffer
214 * Pings the watchdog on write.
216 static ssize_t
bfin_wdt_write(struct file
*file
, const char __user
*data
,
217 size_t len
, loff_t
*ppos
)
225 /* In case it was set long ago */
228 for (i
= 0; i
!= len
; i
++) {
230 if (get_user(c
, data
+ i
))
236 bfin_wdt_keepalive();
243 * bfin_wdt_ioctl - Query Device
244 * @inode: inode of device
245 * @file: file handle of device
246 * @cmd: watchdog command
249 * Query basic information from the device or ping it, as outlined by the
252 static int bfin_wdt_ioctl(struct inode
*inode
, struct file
*file
,
253 unsigned int cmd
, unsigned long arg
)
255 void __user
*argp
= (void __user
*)arg
;
256 int __user
*p
= argp
;
264 case WDIOC_GETSUPPORT
:
265 if (copy_to_user(argp
, &bfin_wdt_info
, sizeof(bfin_wdt_info
)))
270 case WDIOC_GETSTATUS
:
271 case WDIOC_GETBOOTSTATUS
:
272 return put_user(!!(_bfin_swrst
& SWRST_RESET_WDOG
), p
);
274 case WDIOC_KEEPALIVE
:
275 bfin_wdt_keepalive();
278 case WDIOC_SETTIMEOUT
: {
281 if (get_user(new_timeout
, p
))
284 if (bfin_wdt_set_timeout(new_timeout
))
288 case WDIOC_GETTIMEOUT
:
289 return put_user(timeout
, p
);
291 case WDIOC_SETOPTIONS
: {
293 int options
, ret
= -EINVAL
;
295 if (get_user(options
, p
))
298 spin_lock_irqsave(&bfin_wdt_spinlock
, flags
);
300 if (options
& WDIOS_DISABLECARD
) {
305 if (options
& WDIOS_ENABLECARD
) {
310 spin_unlock_irqrestore(&bfin_wdt_spinlock
, flags
);
318 * bfin_wdt_notify_sys - Notifier Handler
319 * @this: notifier block
320 * @code: notifier event
323 * Handles specific events, such as turning off the watchdog during a
326 static int bfin_wdt_notify_sys(struct notifier_block
*this, unsigned long code
,
331 if (code
== SYS_DOWN
|| code
== SYS_HALT
)
338 static int state_before_suspend
;
341 * bfin_wdt_suspend - suspend the watchdog
342 * @pdev: device being suspended
343 * @state: requested suspend state
345 * Remember if the watchdog was running and stop it.
346 * TODO: is this even right? Doesn't seem to be any
347 * standard in the watchdog world ...
349 static int bfin_wdt_suspend(struct platform_device
*pdev
, pm_message_t state
)
353 state_before_suspend
= bfin_wdt_running();
360 * bfin_wdt_resume - resume the watchdog
361 * @pdev: device being resumed
363 * If the watchdog was running, turn it back on.
365 static int bfin_wdt_resume(struct platform_device
*pdev
)
369 if (state_before_suspend
) {
370 bfin_wdt_set_timeout(timeout
);
377 # define bfin_wdt_suspend NULL
378 # define bfin_wdt_resume NULL
381 static const struct file_operations bfin_wdt_fops
= {
382 .owner
= THIS_MODULE
,
384 .write
= bfin_wdt_write
,
385 .ioctl
= bfin_wdt_ioctl
,
386 .open
= bfin_wdt_open
,
387 .release
= bfin_wdt_release
,
390 static struct miscdevice bfin_wdt_miscdev
= {
391 .minor
= WATCHDOG_MINOR
,
393 .fops
= &bfin_wdt_fops
,
396 static struct watchdog_info bfin_wdt_info
= {
397 .identity
= "Blackfin Watchdog",
398 .options
= WDIOF_SETTIMEOUT
|
399 WDIOF_KEEPALIVEPING
|
403 static struct notifier_block bfin_wdt_notifier
= {
404 .notifier_call
= bfin_wdt_notify_sys
,
408 * bfin_wdt_probe - Initialize module
410 * Registers the misc device and notifier handler. Actual device
411 * initialization is handled by bfin_wdt_open().
413 static int __devinit
bfin_wdt_probe(struct platform_device
*pdev
)
417 ret
= register_reboot_notifier(&bfin_wdt_notifier
);
419 pr_devinit(KERN_ERR PFX
"cannot register reboot notifier (err=%d)\n", ret
);
423 ret
= misc_register(&bfin_wdt_miscdev
);
425 pr_devinit(KERN_ERR PFX
"cannot register miscdev on minor=%d (err=%d)\n",
426 WATCHDOG_MINOR
, ret
);
427 unregister_reboot_notifier(&bfin_wdt_notifier
);
431 pr_devinit(KERN_INFO PFX
"initialized: timeout=%d sec (nowayout=%d)\n",
438 * bfin_wdt_remove - Initialize module
440 * Unregisters the misc device and notifier handler. Actual device
441 * deinitialization is handled by bfin_wdt_close().
443 static int __devexit
bfin_wdt_remove(struct platform_device
*pdev
)
445 misc_deregister(&bfin_wdt_miscdev
);
446 unregister_reboot_notifier(&bfin_wdt_notifier
);
450 static struct platform_device
*bfin_wdt_device
;
452 static struct platform_driver bfin_wdt_driver
= {
453 .probe
= bfin_wdt_probe
,
454 .remove
= __devexit_p(bfin_wdt_remove
),
455 .suspend
= bfin_wdt_suspend
,
456 .resume
= bfin_wdt_resume
,
458 .name
= WATCHDOG_NAME
,
459 .owner
= THIS_MODULE
,
464 * bfin_wdt_init - Initialize module
466 * Checks the module params and registers the platform device & driver.
467 * Real work is in the platform probe function.
469 static int __init
bfin_wdt_init(void)
475 /* Check that the timeout value is within range */
476 if (bfin_wdt_set_timeout(timeout
))
479 /* Since this is an on-chip device and needs no board-specific
480 * resources, we'll handle all the platform device stuff here.
482 ret
= platform_driver_register(&bfin_wdt_driver
);
484 pr_init(KERN_ERR PFX
"unable to register driver\n");
488 bfin_wdt_device
= platform_device_register_simple(WATCHDOG_NAME
, -1, NULL
, 0);
489 if (IS_ERR(bfin_wdt_device
)) {
490 pr_init(KERN_ERR PFX
"unable to register device\n");
491 platform_driver_unregister(&bfin_wdt_driver
);
492 return PTR_ERR(bfin_wdt_device
);
499 * bfin_wdt_exit - Deinitialize module
501 * Back out the platform device & driver steps. Real work is in the
502 * platform remove function.
504 static void __exit
bfin_wdt_exit(void)
506 platform_device_unregister(bfin_wdt_device
);
507 platform_driver_unregister(&bfin_wdt_driver
);
510 module_init(bfin_wdt_init
);
511 module_exit(bfin_wdt_exit
);
513 MODULE_AUTHOR("Michele d'Amico, Mike Frysinger <vapier@gentoo.org>");
514 MODULE_DESCRIPTION("Blackfin Watchdog Device Driver");
515 MODULE_LICENSE("GPL");
516 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR
);
518 module_param(timeout
, uint
, 0);
519 MODULE_PARM_DESC(timeout
, "Watchdog timeout in seconds. (1<=timeout<=((2^32)/SCLK), default=" __MODULE_STRING(WATCHDOG_TIMEOUT
) ")");
521 module_param(nowayout
, int, 0);
522 MODULE_PARM_DESC(nowayout
, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT
) ")");